JPS60228568A - Dichroic dye for liquid crystal - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a dichroic dye that is dissolved in a liquid crystal and used in a liquid crystal device such as a liquid crystal display device and a liquid crystal light valve, which utilizes the dust-host effect.

[Technical background of the invention]

In general, it is ideal for a liquid crystal device, such as a display device, that utilizes the dust-host effect to be able to display images with good contrast, have quick response to display driving, and display colors that do not fade over a long period of time.

By the way, the display contrast of a dust-host type liquid crystal device is mainly determined by the dichroic ratio of the dichroic dye mixed into the liquid crystal, and the higher the dichroic ratio, the better the display contrast.

However, even if the dichroic ratio of the dye is high, if the coloring ability of the dye itself is low, the displayed color becomes pale and sufficient display contrast cannot be obtained.

If the coloring ability of the dye is low, it is necessary to increase the amount of the dye added to the liquid crystal to make the displayed color darker, but this will have a negative effect on the liquid crystallinity of the liquid crystal molecules and reduce the responsiveness to display driving. Deteriorate. It is also important that the dichroic dye has sufficient compatibility with the liquid crystal. If the dichroic dye has low compatibility with the liquid crystal, the dye may precipitate into the liquid crystal (this dye precipitation is noticeable at low temperatures), which causes color unevenness in the display area and deteriorates the display quality. It may cause a decline.

That is, in order to obtain the ideal dust-host liquid crystal device as described above, the dust dichroic dye mixed into the host liquid crystal must: 1. have a high dichroic ratio; 2. have a high dichroic ratio; It must have coloring ability, and a sufficiently deep display color can be obtained with a small amount of addition; and (3) it must have sufficient compatibility with liquid crystals and not precipitate even at low temperatures.

Conventionally used dichroic dyes include benzene-based azo dyes, stilbene-based dyes, and anthraquinone-based dyes, but none of these conventional dyes can be said to satisfy all three requirements above. [Objective of the Invention] Therefore, the object of the present invention is to provide a liquid crystal device that has a high dichroic ratio and coloring ability, has good compatibility with liquid crystals, and is suitable for use in a liquid crystal device that utilizes the dust-host effect. An object of the present invention is to provide a dichroic dye.

[Key points of the invention]

The dichroic dye of the present invention comprises at least one cheno(2,3-d)-thiazole azo compound represented by formula (I).

In the above formula (1), each X and Y are each independently 1 and each R1 and R2 are each independently hydrogen, a 710g atom, a cyano group, a thiocyano group (-8CN), a hydroxy group, a mercapto group (- 8R), lower alkyl group,
Fluorinated lower alkyl group (i.e., a group derived by substituting at least one hydrogen atom of a lower alkyl group with a fluorine atom), a lower alkylsulfonyl group (-
802-R), fluorinated lower alkylsulfonyl group (i.e., a rheta group derived by substituting at least one hydrogen atom of a lower alkylsulfonyl group with a fluorine atom), lower alkoxy group, lower alkylthio group (-8R
), -OR-0-R group, -R-OR group, lower alkylcar R-nyl group (-COR), lower acyloxy group (-0
COR), lower alkoxylic? Nil M (-COO
R'), -@)-R10 group, -0-R'' group, O5R1
0M, -0-C)-R" group, -R*-o-R10 group,
or -R-σ>R10 group; each R3 is independently hydrogen, a rhodane atom, a methyl group, an ethyl group, a methoxy group, an ethoxy group, a cyano group, or a trifluoromethyl group (-〇F3): R5 and R are each independently hydrogen, a lower alkyl group, a lower hydroxyalkyl group (-R*-OH), a halogenated lower alkyl group (i.e. 1, at least one hydrogen atom of the lower alkyl group is replaced with a halogen atom) group derived by), cyano lower alkyl group (-R
"-CN), each R is independently hydrogen or a lower alkyl group; each R is independently a lower alkyl group; each R is independently a hydrogen or lower alkyl group; each P10" Each R is independently a hydrogen, a lower alkyl group, or a lower alkoxy group; each R is independently a lower alkyl group; each R* is
each independently represents a lower alkylene group; l and j each represent 0''&or 1; p represents an integer from 1 to 4; and n represents an integer from 1 to 8.

In this specification and claims, the term "lower" when used in reference to groups such as alkyl and alkylene groups refers to groups having from 1 to 8 carbon atoms.

As can be seen from the definition of formula (1) above, the dichroic dye of the present invention comprises a monoazo compound represented by the formula, a disazo compound represented by the formula (where W is X or Y), and a disazo compound represented by the formula It contains a trisazo compound.

In the above formula (1) or product), R1 is preferably hydrogen, a halogen atom, a cyano group, or a lower alkyl group, R2 and R3 are each preferably hydrogen, and R is preferably Each independently is a lower alkyl group or a cyano lower alkyl group, and n is preferably a lower alkyl group.

Further, the dichroic dye of the present invention is preferably a disazo compound represented by formula (2) and a trisazo compound represented by formula (trans). In the case of a disazo compound, in the formula (to), W is 1.4-F, and W is 1.4-F.
4-naphthylene group, and in the case of a trisazo compound, in the formula (transformation), X and Y are each 1#
Particularly preferred are 4-7x nylene and those in which X is a 1,4-phenylene group and Y is 1,4.

That is, the most preferred dichroic dye of the present invention is one represented by the following general formula.

(In the formulas (■ to (■), R1' and R4' represent the above-mentioned preferred R and R groups, respectively.) Now, the dichroic dye of the present invention is a 2-aminocheno[2,3 -d] can be prepared starting from diazotization of a thiazole compound. This diazotization is carried out in a mineral acid such as sulfuric acid or phosphoric acid or in an organic acid such as acetic acid or a propionic acid/acetic acid mixture. This can be carried out by reacting a thiazole compound with approximately equimolar amounts of a diazotizing agent such as nitrosyl sulfate and sodium nitrite under water cooling.This diazotization produces the corresponding chenothiazole diazonium salt.This diazonium The salt is used in the next coupling step without being isolated from the reaction mixture.

The monoazo compound represented by formula (n) is obtained by converting the reaction mixture containing the above chenothiazole diazonium salt into acetic acid or a mixture of acetic acid and propionic acid and having the formula H-Z (where z is the previously defined formula). It can be obtained by reacting with a coupling component. This coupling reaction takes place at comparatively low temperatures (e.g. -30°C to 15°C):
cormorant. Generally, this coupling is completed in 1-3 hours. The coupling component is preferably used in excess (for example, 2 to 4 times the molar amount) relative to the diazo component.

In this reaction, when an aromatic primary amine such as aniline is used as a coupling component, more diazoamino compounds are produced than the desired aminoazo compound (i.e., when aniline is used as a coupling component) (If the aniline is present, coupling is more easily carried out on the carbon para to the amino group of the aniline, as well as on the amino group itself). Therefore, in order to obtain the desired aminoazo compound in a higher yield, the amino group of the aniline to be used should be protected with, for example, sodium methanesulfonate, as will be detailed in the following examples. Preferably, the coupling is preferentially carried out on the carbon in the position relative to the group. After completion of this coupling, the coupling product is heated (e.g., at 60 to 90°C) in an alkaline medium (e.g., aqueous sodium hydroxide solution) to remove the retained group.As a coupling component, α - Such problems do not occur when naphthylamine is incorporated.

The disazo compound represented by the formula (to) can be produced by the following method. That is, the reaction mixture containing the chenothiazole diazonium salt is first subjected to a coupling reaction with a primary amine represented by 2H-W-Nu2 (where W is the same as previously defined). The conditions for this coupling reaction are the same as those in the production of the monoazo compound described above. This coupling yields an aminoazo compound of the formula: This aminoazo compound is diazotized in the same manner as the diazotization reaction of chenothiazole described above. This diazotide is then coupled with a coupling component represented by the above formula H-Z. This coupling is carried out in the same manner as the coupling reaction of the monoazo compound described above. In this way, a disazo compound represented by formula (g) is obtained.

The trisazo compound represented by the formula (Foundation) is the chenothiazole diazonium salt represented by the formula H-X-NH.

(wherein, Produced by coupling with the primary aban represented by formula can. Each diazotization and coupling reaction during this manufacturing process occurs in the same manner as described above. Each final product obtained can be purified using a silica gel column or by recrystallization. The starting material for the dichroic dye of this invention, the chenothiazole compound of formula (1), is, for example, J
Our own fur praktisehe Che
mie e 315 [3], 539-548 (1973
) and British Patent No. 1.549.185, including its production method, or can be produced by appropriately modifying the method described in that document. and a group in which R is other than hydrogen) do not directly couple with the diazonium salt. In that case, -OH or -8H) is first coupled with a diazonium salt, and then the resulting diazo compound is subjected to reactions known per se, such as alkylation and esterification, depending on the target compound, to produce the desired final product. Try to get things.

[Embodiments of the invention]

Next, the present invention will be explained in detail with reference to the following examples.

2-amino-5-n-butyl-cheno(2,
3-d) Thiazole 4.24 grams (0.02 mol) t
It was added to -85q6 phosphoric acid 40g and heated to 70°C to dissolve. After cooling this solution to -5 to 0°C, 5.9 g of 43% by weight nitrosyl sulfuric acid was gradually added dropwise over 30 minutes. After the dropwise addition was completed, the reaction mixture was stirred at -5 to θ°C for 1 hour to complete diazotization.

On the other hand, N-phenylpyrrolidine (coupling component) 8
．． A solution of the coupling component was prepared by dissolving 82 grams (0.06 mol) in 100 rats of a 1:1 mixture by weight of acetic acid-propionic acid. The reaction mixture containing the diazotized product was added dropwise to the coupling component solution at -5 to 0° C. over 40 minutes while stirring, and the mixture was stirred at the same temperature for 2 hours.

Thereafter, the reaction mixture was poured into 300 m of ice water, and the precipitate was filtered off, washed with water, and dried under vacuum. 2 grams of the obtained crude monoazo compound was dissolved in 50 ml of chloroform, and 20 grams of alumina powder was added under stirring, followed by filtration and washing with chloroform. Next, mother liquor i30
The mixture was concentrated to 300 mm and purified using a column with an inner diameter of 3 cr. The eluate was evaporated to dryness, and this was recrystallized twice from a chloroform-methanol mixed solvent to obtain the desired dichroic dye. Desired dichroic dyes were obtained in the same manner as in Example 1, except that .

Table 1 Example 6 (A) 2-amino-5-n-butyl-cheno[2,3-
d) 4.24 g (0.02 mol) of thiazole were diazotized as in Example 1. This diazotized reaction mixture was combined with 8.58 grams of α-naphthylamine (0.06
1 mole] dissolved in 150 moles of acetic acid with stirring.
The mixture was added dropwise at 0° C. over 30 minutes and stirred at the same temperature for 2 hours. This reaction mixture was poured into 400 d of ice water, and the precipitate was filtered off and washed with water. The obtained cake was added to aqueous sodium carbonate solution, stirred for 30 minutes, filtered, and dried under vacuum to obtain 68 grams of the crude aminomonoazo compound represented by the formula (B) The above aminomonoazo compound 3 gram into 300 ml of a 1:1 mixture by weight of acetic acid-propionic acid, then 2.4 grams of 43% nitrosyl sulfuric acid was added under stirring at a temperature of -10 to -5°C, and at the same temperature 1. Diazotization of the aminoazo compound was achieved by stirring for hours. Diazotized reaction mixture e IILN-diethylaniline6.
2 grams of a 1:1 mixture by weight of acetic acid-propionic acid 10
0iA! The solution was added dropwise at -5 to O<0>C and stirred at the same temperature for 2 hours. Add 150ml of ice water to this reaction mixture.
/ was added, and the precipitate was filtered off, washed with water, and dried under vacuum to obtain 2 grams of a crude bisazo compound.

This crude bisazo compound was purified in the same manner as in Example 1 to obtain 0.4 g of the desired dichroic dye.

Example 7 2-amino-5-n as 2-aminochenothiazole
A desired dichroic dye was produced in the same manner as in Example 6 except that -propyl-cheno(:2.3-d)thiazole was used.

Example 8 A desired dichroic dye was produced in the same manner as in Example 6 except that 2-amino-5-benzyl-cheno(2,3-d)thiazole was used as 2-aminochenothiazole.

Example 9 2-amino- as a 2-aminochenothiazole compound
A desired dichroic dye was obtained in the same manner as in Example 6 except that 5-cyano-cheno[2,3-d]thiazole was used.

Example 10 Example 1 except that the aminomonoazo compound obtained in step (4) of Example 6 was coupled with ferμ in step (B) of Example 6, and the obtained diazo compound was butylated. A desired dichroic dye was obtained in the same manner as in Example 6.

Example 11 (A) 2-amino-5-n-butyl-cheno(2,3-
d) 4.24 g (0.02 mol) of thiazole were diazotized analogously to Example 1. This diazotized reaction mixture was mixed with 16.7 g (0.08 mol) of sodium aniline-ω-methanesulfonate represented by the formula in 1 part of a 50% aqueous acetic acid solution.
It was added dropwise to the solution dissolved in 00- at 10° C. over 30 minutes while stirring, and stirred at the same temperature for 2 hours. This reaction mixture was stirred at 30° C. for 30 minutes, then poured into 500M water, and the precipitate was filtered out and washed with water. The obtained cake was added to aqueous sodium carbonate solution and heated at 65°C for 2 hours.
After heating at 80 to 85°C for 30 minutes, it was cooled, filtered, and vacuum-dried to obtain a crude aminomonoazo compound represented by the formula (B) Example 6 except that the above aminomonoazo compound was used. j5 by the same process as step (B)
Coupling of N,N-diethylaniline was performed to obtain the desired dichroic dye charge.

Example 12 A desired dichroic dye was obtained in the same manner as in Example 11, except that 2-amino-5-benzyl-cheno(2,3-d:l]thiazole was used as the chenothiazole compound.

Example 13 A desired dichroic dye was produced in the same manner as in Example 11, except that the aminomonoazo compound obtained in Example 11 (4) was mixed with N-methyl-N-cyanoethyl-aniline.

Example 14 A desired dichroic dye was produced in the same manner as in Example 11, except that the aminomonoazo compound obtained in Example 11 was subjected to N-ethyl-N-cyanoethyl-aniline coupling.

Example 15 Example 1 except that the aminomonoazo compound obtained in Example 11 (4) was coupled with N-phenylmorpholine.
The desired 20 dye was prepared in the same manner as in Example 1.

Example 16 The aminomonoazo compound obtained in Example 11 was added to Example 11.
A desired dichroic dye was produced in the same manner as in Example 11, except that in (B), the resulting disazo compound was coupled with phenol and butylated.

Example 17 (A) 2-amino-5-methyl-cheno[2,3-d]
3.4 grams (0.02 mol) of thiazole were dissolved in 60 g of a 1:1 mixture by weight of acetic acid-propionic acid. To this solution was added 5.9 grams of 43tinitrosyl sulfate (0,02
mol) was added over 30 minutes and stirred at the same temperature for 1 hour to complete diazotization. The diazotized reaction mixture with sodium aniline-ω-methanesulfonate 16.
7 grams (0.08 mol) in 100ml of 50 thiacetic acid aqueous solution
It was added dropwise to a solution dissolved in 1 over 30 minutes at 10° C. under stirring, and stirred at the same temperature for 2 hours.

The reaction mixture was stirred at 30°C for 30 minutes, then 50% water
The mixture was poured into a 6-proof medium, filtered, and washed with water. The obtained cake was added to a dihydric sodium hydroxide aqueous solution 300% and heated at 65°C.
After heating for 2 hours at 85° C. and 30 minutes at 85° C., the mixture was cooled, filtered, washed with water, and dried under vacuum. In this way, 4.5 grams of a crude aminomonoazo compound represented by the formula was obtained.

(B) Add 4.5 g of the above aminomonoazo compound to 200 mA' of acetic acid-deropionic acid mixture in a weight ratio of 1:1, cool to -10 to -5°C, and then add 4.8 g of 431 nitrosyl sulfate to 10 The diazotization was completed by stirring for an additional hour at the same temperature. This reaction mixture was dissolved in a solution of 12 grams of α-naphthylamine dissolved in 100 d of a 1:1 mixture by weight of acetic acid-derobionic acid.
The mixture was added dropwise over a period of time, and the mixture was further stirred for 3 hours. 1001 rL of water was added to this reaction mixture, the precipitate was filtered, washed with water, and washed with an aqueous IJ solution, further washed with water, and dried under vacuum to obtain a crude aminodisazo compound represented by the formula 3.8 Got a gram.

(C) 3.8 grams of the above aminodisazo compound was ground in a mortar, and acetic acid-deropionic acid mixture 2 was prepared in a weight ratio of 1:1.
00d, and the mixture was cooled to -5°C to 0°C, and 2.6 g of 43 tinitrosyl sulfate was added dropwise over 10 minutes while stirring. This reaction mixture was stirred at the same temperature for 1 hour to complete diazotization. This diazotized reaction mixture was added dropwise at 10°C to a solution of 12 grams of N,N-diethylaniline dissolved in 100 d of acetic acid, and after stirring for 3 hours, 200 d of water
added. The precipitate was filtered off, washed with water, and dried in vacuum. Two grams of this crude product was purified in the same manner as in Example 1 to obtain 0.3 grams of the desired dichroic dye.

Example 18 In Example 17(A), 2-amino-5-n-propyl-cheno(2,3
-d) A desired dichroic dye was produced in the same manner as in Example 17 except that thiazole was used.

Example 19 In Example 17 (4), 2-amino-5-n-butyl-cheno[2,3-d
] O was prepared in the same manner as in Example 14 except that thiazole was used. Example 20 In Example 17 (4), 2-amino-5-benzyl-chenothiazole compound was used. (2,3-d
) A desired dichroic dye was prepared in the same manner as in Example 17 except that thiazole was used.

Example 21 A desired dichroism was obtained in the same manner as in Example 17 except that the aminodisazo compound obtained in Example 17(B) was coupled with N-methyl-N-cyanoethylaniline in Example 17(C). I got the dye.

Example 22 In Example 17(A), 2-amino-5-n-butyl-cheno[2,3-d]thiazole was used, and the obtained aminodisazo compound was used in Example 17(C') as N.
A desired dichroic dye was obtained in the same manner as in Example 17 except for coupling with -methyl-N-cyanoethylaniline.

Example 23 Example 1 except that the aminodisazo compound obtained in Example 17(B) was coupled with phenol in Example 17(C), and the obtained trisazo compound was dithylated.
A desired dichroic dye was obtained in the same manner as in Example 7.

Example 24 As a chenothiazole compound, 2-amino-5-n-
A desired dichroic dye was obtained in the same manner as in Example 23 except that butyl-cheno[2,3-d]thiazole was used.

Example 25 Similar to Example 11(A), 2-amino-5-methyl-
A corresponding aminomonoazo compound was prepared using cheno(2,3-d)thiazole, and this aminomonoazo compound was coupled with aniline in the same manner as in Example 11(A) to obtain an aminodisazo compound. This aminodisazo compound was prepared in the same manner as in Example 11 (B) to obtain N,N-
Coupling with diethylaniline gave the desired dichroic dye.

Examples 26 to 28 Desired dichroic dyes were obtained in the same manner as in Example 25, except that the 2-amino-chenothiazole compound and H-Z shown in Table 2 below were used.

Table 2 Table 3 lists the structural formulas and properties (maximum absorption wavelength (λm & λ, hue, and dichroic ratio) of the dichroic dyes produced in Examples 1 to 28 above.

The properties shown in Table 1 are as follows: each dichroic dye was mixed with BDH Chemical's biphenyl liquid crystal E7 (dielectric ◇ nematic liquid crystal with positive anisotropy).
．． Using a liquid crystal material dissolved in a proportion of 0% by weight, this is
The results were obtained by incorporating and measuring a negative display type dust host type liquid crystal display device as shown in FIG. 1, which will be described in detail below.

In dust-host liquid crystal devices of different types, the characteristics of each dye may exhibit slightly different values.

Examples 29 to 55 Dichroic dyes shown in Tables 4 to 7 below were produced according to each of the above Examples. The characteristics are also listed in Tables 4 to 7. In addition, the characteristics of the dichroic dyes of Examples 29 to 55 are also the same as those of Examples 1 to 2.
It was obtained in the same manner as dichroic dye No. 8.

The dichroic dye of the present invention comprising at least one compound represented by the above general formula (1) has a high dichroic ratio,
It has a large coloring ability and can provide the necessary and sufficient display color with a small amount, has good compatibility with liquid crystals, and does not precipitate even at low temperatures. Therefore, by combining the dichroic dye of this invention with various types of liquid crystals (hosts) and incorporating it into a liquid crystal device that utilizes the dust-host effect, it is possible to display images with good contrast and excellent responsiveness. , a liquid crystal device whose display colors do not fade over a long period of time can be obtained.

There is no 4IJC restriction for liquid crystals used in combination with the dichroic dyes of this invention. Schiff base type, azo type, azoxy type, cyclohexyl ester type, phenylcyclohexane type, biphenyl type, terphenyl type, dioxane type,
Various liquid crystals such as pyrimicin-based liquid crystals can be used in combination with the dichroic dye of this invention. Specific examples of liquid crystals are described, for example, in "Basics and Applications of Liquid Crystal Electronics" (Ohmsha, 1979), edited by Akio Sasaki, especially on pages 207 to 214. Any of these liquid crystals can be used alone or in combination,
Can be used.

The amount of the dichroic dye of the present invention added to the liquid crystal should be within a range that does not affect the operation of the liquid crystal molecules, and usually this amount is preferably about 0.1 to 5% by weight of the liquid crystal. .

Further, the dichroic dye of the present invention may be added to the liquid crystal alone, or may be added to the liquid crystal together with other dichroic dyes or isotropic dyes. In either case, the total amount of dye added to the liquid crystal is preferably up to 5% by weight based on the weight of the liquid crystal.

As mentioned above, the dichroic dye of the present invention can be used in various liquid crystal devices that utilize the dust-host effect.

FIG. 1 shows a negative display type dust-host type liquid crystal display device in which liquid crystal molecules are arranged homogeneously.
A host liquid crystal 14 and a dichroic dye 15 of the present invention are filled between the electrodes 1 and 2 (at least the electrode 1 is optically transparent).

Note that the inner surfaces (surfaces in contact with the liquid crystal) of both electrode substrates 11.12 are subjected to horizontal alignment treatment (substrates 11.12).
810 on the inside. The thickness of the entire liquid crystal layer is 10 μm (after applying PT oblique evaporation or applying polyimide resin and then rubbing with cotton cloth, etc.). And both electrode substrates 11.1
2 is connected to an external power source 16 that applies an electric field between both substrates 11 and 12. In addition, the electrode substrate 11 on the display surface side
A polarizing plate 1 is placed on the outer surface of the
7 is provided, and the light transmission axis of this polarizing plate 17 is aligned with the long axis direction of the homogeneously aligned liquid crystal molecules and dye molecules.

In this dust-host type liquid crystal display device.

When a biphenyl liquid crystal E7 manufactured by BDH Chemical Co., Ltd. was used as the host liquid crystal 14, and 0.7% by weight of the dye shown in Table 30-6 was added as the dichroic dye 15, this display device could be used without applying any voltage. The hour is colored in clear blue, 32
When a voltage of 3 V was applied, the electric field application part became colorless. The dichroic dye exhibited a maximum absorption wavelength of 626 NFF1% dichroism ratio of 8.4 in the host liquid crystal, and the display contrast of this display device was extremely good. Furthermore, the dichroic dye had sufficient compatibility with liquid crystals, and no precipitation was observed even at low temperatures. In addition, when other dichroic dyes listed in Tables 3 to 7 are used in this type of dust-host liquid crystal display device, the maximum absorption wavelength, hue, and dichroic ratio of each dichroic dye are as follows: When using any of the dichroic dyes shown in Tables 3 to 7, the display contrast of the display device was extremely good. Furthermore, these dichroic dyes also have very high coloring ability and are also excellent in compatibility with host liquid crystals. Although the dichroic dyes shown in Tables 3 to 7 above have been explained here, not only these dyes but also all the dichroic dyes represented by the general formula (1) have similar performance. Similar effects can be obtained even when two or more of these dyes are used in combination.

FIG. 2 shows a White-Taylor type dust-host type liquid crystal display device, in which a pair of electrode substrates 2, at least one of which is transparent to light, are bonded via a sealing material 23.
A host liquid crystal 24 containing an optically active substance known per se and a dichroic dye 25 of the present invention are filled between 1 and 22. The inner surfaces of both electrode substrates 21 and 22 are horizontally aligned, and the total thickness of the liquid crystal layer is 10 μm.
It becomes. And the both electrode substrates 21 * 2
An external power supply 26 for applying an electric field between the side substrates J1 and 22 is connected to the side substrates J1 and 22. (Liquid crystal used in the display device shown in Figure 1)
4-(2-methylbutyl)-4' as an optically active substance
-Cyanobiphenyl (chiral nematic liquid crystal) t-
A dichroic dye containing 25% by weight was used.
When 1% by weight of the dichroic dye No. 41 in Table 3 was added, this display device was colored bright red when no voltage was applied, and when a voltage of 32 Hz = 6 V was applied, the electric field application section It became colorless.

The dichroic dye has a maximum absorption wavelength of 532 nm.
%-chromaticity ratio of 8.6, and the display contrast of this display device was extremely good. In addition, the dichroic dye has sufficient compatibility with liquid crystals and has a low temperature (e.g.
No precipitation was observed even at a temperature of 5°C.

The dichroic dyes that can be used in this White Taylor type guest-host type liquid crystal display device are not limited to the dyes of A1 above, but also the other dyes shown in Tables 3 to 7 above and other dyes of general formula (1). The same effect can be obtained even if the dichroic dye represented by ) is used or a mixture of two or more of these dyes is used.

Is the liquid crystal molecules homeotropically aligned in Figure 3? A pair of electrode substrates 31 are bonded together via a sealing material 33.
．． 32 is filled with a host liquid crystal 34 and a dichroic dye 35 of the present invention. The inner surfaces of both electrode substrates 31 and 32 are subjected to vertical alignment treatment (the alignment agent is a silane compound such as n-octadecyltriethoxysilane), and the total thickness of the liquid crystal layer is 10 μm. There is.

A side substrate 31.3 is attached to both electrode substrates 31.32.
An external power source 36 is connected to apply an electric field between the two.

In this dust-host type liquid crystal display device, EN-24 (nematic liquid crystal with negative dielectric anisotropy) manufactured by Chisso Corporation is used as the host liquid crystal 34, and 2 weights of the following chiral nematic liquid crystal H5 as an optically active substance is added. When a total of 1.2% by weight of the dye A14 in Table 1 was added as the dichroic dye 35, this display device was colorless when no voltage was applied;
When a voltage of 3 V at Hz was applied, the electric field application section was colored bluish-purple. The dichroic dye had a maximum absorption wavelength of 5931111% in the host liquid crystal and a dichroic ratio of 10.3, and the display contrast of this display device was extremely good. Furthermore, the dichroic dye had sufficient compatibility with liquid crystals, and no precipitation was observed even at low temperatures.

Note that dichroic dyes that can be used in this positive display type dust-host type liquid crystal display device are not limited to the dyes of A14 above, but also other dyes of the above Tables 3 to 7 and others of the above general formula (1). Even if a dichroic dye represented by is used,
Similar effects can also be obtained by using a mixture of two or more of these dyes.

As described above, the liquid crystal device using the dichroic dye of the present invention is as follows:
Although a display device has been described with reference to FIG. 3 (not shown), the liquid crystal device using the dichroic dye of the present invention is not limited to a display device, but also includes a liquid crystal light valve device including a liquid crystal shutter device. It is something to do. The structure of the liquid crystal light valve device is not shown because it is substantially the same as the display device shown in FIGS. 1 to 3.

That is, the dichroic dye of the present invention comprises a pair of electrodes, at least one of which is transparent; a liquid crystal material filled between the pair of electrodes; at least one type of liquid crystal; and at least one liquid crystal material dissolved in the liquid crystal; It can be used in any liquid crystal device that utilizes the dust-host effect, comprising the dichroic dye of this invention of the type; and having means for applying a voltage to a pair of electrodes.

〔Effect of the invention〕

According to the present invention, it is possible to provide a dichroic dye having a high dichroic ratio, high coloring ability, and excellent compatibility with liquid crystals.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of a negative display type dust-host type liquid crystal display device, and Figure 2 is a cross-sectional view of a white-Taylor type dust-host type liquid crystal display device.
FIG. 3 is a sectional view of a positive display type dust host type liquid crystal display device. 11.12, 21.22.31.32 mountain electrode substrate, 13
, 23.33...Sealing material, 14°24.34...
Host liquid crystal, 15, 25.35... dichroic dye, 16
, 26.36... External power supply, No. 2... Polarizing plate.

Claims (1)

[Claims] General formula (Each R and R are independently hydrogen, a halogen atom, a cyano group, a thiocyano group, a hydroxy group, a mercapto group, a lower alkyl group, a fluorinated lower alkyl group, a lower alkylsulfonyl group) , fluorinated lower alkylsulfonyl group,
Lower alkoxy group, lower alkylthio group, -OR''-0
-R0 group -R-OR group, lower alkylcarzenyl group, lower acyloxy group, lower alkoxycarbunyl group,
+R group, -〇beg〆R10 group, -0-R group, -〇0R group, -R"<H2R10 group, or -R*-C)-R10 group; each R is independently, Hydrogen, halogen atom, methyl group, ethyl group, methoxy group, ethoxy group, cyano group or trifluoromethyl group; -K] group, -0R10 group, -
n-R'° group, (-) -W group, 5-OR' group, -8R' group or 100OR8 group: (-) R and R each independently represent hydrogen, lower alkyl group, lower hydroxy Alkyl group, halodanated lower alkyl group, cyano lower alkyl each R7 is each independently hydrogen, lower alkyl each 88 is each independently a lower alkyl group or eit10 group; each R9 is each independently hydrogen or lower alkyl Group; Each R10 is each independently hydrogen, a lower alkyl group, or a lower alkoxy group; Each R0 is each independently a lower alkyl group; each R* is each independently a lower alkylene group; 1 and j are each , Ol or 1: p is an integer from 1 to 41; and n is an integer from 1 to 8).